To Dance with the Devil
by KetKat
Summary: Thrown straight into the clutches of the Mastermind himself, Fiona has to risk her morality, life and conscience in order to survive Moriarty's games. But it seems she is no ordinary Police Inspector, and she might not be such an easy opponent after all. M for violence and smut.


A/N Hey everyone! This is the first OC fic I've uploaded, so I hope you like it. Just as a warning, there will be themes of violence and sexual content in this story, hence why it has an M rating. (But there won't be any major character death - I'm not that mean!)

KetKat xo

* * *

I have many flaws.

The first is that I'm too nice, and everyone knows it. Especially my colleague, Lestrade. He saunters into our office, letting his files collapse onto his desk with a loud _thunk_. Peering up at him, I noticed that his usual relaxed smile was gone, replaced with a frown that crinkled his forehead. Well, this was rather strange…

'Lestrade?' I decided to tread carefully, not making any movement to stand as his eyes bored into mine. 'You alright?'

'Today's the day, Fi.' That was all he said, slumping into his office chair and not kicking his legs up onto the keyboard for once.

Oh.

Today was the day that we infiltrated a gathering for Moriarty's supporters. It'd taken months to extract the information from our only source. He'd just been sat in his cell, rocking his knees back and forth and expecting to be shot at any minute. The worst part was that we had no idea if what he had told us was true: all we knew was at the Hartnoll Hotel tonight, a group of 100 inconspicuous businessmen were going to gather there. And of course, discuss "politics." The staff had been bought off by the sounds of it.

I'd seen Lestrade grow more and more agitated as the date of the gathering drew closer, watching the man pore over mountains of records and files to establish our plan as the police. But I'd also known he'd grown no closer to a solution, because as it turns out, turning up on the doorstep of the hotel would get you kicked out, or shot. It was something Lestrade had failed to grasp until this morning, it seems.

'I know.' I'd let the silence stretch out for too long, realising that Lestrade's mind was probably a minefield of distress right now. He was still looking at me, or rather, through me. What I'd said hadn't registered with him at all.

'Lestrade, if you need ti-'

'I don't need time Fiona, I've had all the bloody time in the world since Wells spilled the details about the gathering! What I need is….' He stopped himself, his eyes now actually snapping onto mine, a grin forming on his expression.

'-A woman.' Delight practically radiated from his body, leaping to his feet, approaching my desk like he'd won the lottery.

'Fi, you're a woman!' He began again, still coming closer, limiting the distance between us. Air escaped me in a snort, adopting a sour tone.

'Took you long enough to notice.'

Unfortunately, this didn't shake him. 'We need someone who can go into the Hotel and not look suspicious… who better than you Fi? You're totally suited for this job.'

'Am I really?' I was dripping with sarcasm, folding my hands on my lap, completely unimpressed. In all honesty I just wanted to wipe the eager look from his face, it was never a good sign…

'Sure, you're plain enough for nobody to pay attention to you.'

With that I rose to my feet carefully, controlled. I couldn't help it. I flicked my hair over my shoulder, straightening myself up, and extending one middle finger towards my colleague's face. 'You really know how to flatter a lady.' I left Lestrade to fester, hoping he'd realised how much he'd offended me.

Going back to my first flaw…

That night I found myself in a taxi to the Hartnoll hotel.

* * *

I relentlessly beat at the ruffles on my dress, considering the sheer dangerousness of this mission. Lestrade had given me a fake ID, just in case things went downhill and they discovered I was with the police. Instead of being Fiona Hart, I was now Leila Monroe. Clearly not my real name… but who would question it here?

The dress I wore was a rich turquoise, lying in stark contrast to my pale skin and copper hair. I felt self-conscious for a number of reasons: I didn't have a weapon, I loathed dresses, and I'm pretty sure I'd just look like an awkward ginger lurking in the background.

Cautiously climbing out of the taxi, I raised my chin with confidence, approaching the bouncers with as much elegance as I could muster. I was almost surprised, it seemed the whole hotel had been cordoned off for this event, considering the lack of other vehicles and the security at the front entrance. I could feel their eyes on me as I whipped out my identification, purring in a French accent.

'Plus one for _ze_ gathering.' They exchanged a knowing look with each other, noting that I was not one of their regular guests. The bouncers stepped back, allowing me passage into the area that an avid following of Moriarty would be occupying.

For a moment the only thing I could take in was the sea of suits. Everywhere I looked, men in arrays of black and brown suits congregated around tables, whispering in hushed tones to each other. There were few breaks in the almost silence, and that was when the occasional raucous laughter filled the room.

I was the sole woman here.

Instantly I cursed Lestrade, pulling my phone out of my bra (where else was I going to keep it in a dress this tight?) And sending him an angry text.

_'I'm the only woman here, dammit Greg.'_

Sighing to myself, I hastily replaced my phone and scanned the crowds again, considering who to approach.

My eyes snapped to the ring in the middle, all centred around one man. It took less than a second to realise that Moriarty must be in the middle - the mastermind I was risking my life to see in the flesh. He was shorter than what I'd expected, donning a simple beige suit and cream tie. It was definitely a sharp difference to his followers, who all seemed to blur into the same circle of flashy suits and slicked back hair. It was like seeing a diamond amongst shards of glass.

_A diamond who wouldn't hesitate to rip your flesh off._ I shuddered inwardly, drawing my black shawl around my dress protectively, trying to feel less exposed as I took a tiny step closer. Their words were barely audible, much to my irritation.

One of them looked over, a lopsided grin forming on his face as he broke away from Moriarty's circle, making a beeline for me. Upon closer inspection, his cheeks appeared rosy under the light, eyes filled with a dazed look. The stench of alcohol wafted over before he'd even reached me.

'Why's a lil girly like you here? We're talking about important business stuff.' He gurgled, throwing an arm around my shoulder. Sweat beaded on his forehead, grin sickly. I resisted the urge to gag, placing the sweetest smile I could on my face.

'What a coincidence, me too! I'm here on behalf of my boss, he's currently…. Indisposed.' Well, at least part of it was true; I _was_ here on behalf of the police. His brow furrowed in confusion, attempting to process my words.

'Indisposed? What ya mean?' his grip tightened on me for a moment, before stepping back, taking me in. I simply let my smile remain on my face, appearing relaxed.

I chuckled lightly, an airy rasp which permeated through the deep rumbles and murmurs of the males around me. I crooked my head slightly, offering the lopsided grin he'd given me earlier.

'It means, darling, that he is currently lying in a ditch somewhere.'

I hadn't expected the whole room to fall into silence. Heads turned, craning their necks in my direction, finally acknowledging my presence. Even Moriarty's group peeked over, curious, suspicious. I tilted my chin up slightly, appearing confident, arrogant even. I knew it was the only way to ride out the wave of attention. The man still appeared confused, shock breaking through his drunken stupor. 'Y-You mean, you murdered someone?' He took another step away from me, fear growing in his eyes.

I could still feel gazes set in my direction; I needed to play this carefully. 'Of course not sweety, you must understand that I'm very grieved for the loss of my supervisor. His car just... skidded out of control, there was nothing I could do.' I let sadness mock my expression, hearing laughter perpetrate from the corners of the room. One of the man's friends from Moriarty's circles padded over, placing a hand on his shoulder, murmuring.

'Why don't we go back and see Jim? I bet he's got some real interesting stories to tell you.' The drunken man nodded weakly, a haunted expression shadowing his face as he turned away from me. I honestly couldn't understand why he was so shocked; he was in a room with corrupt criminals and businessmen?

Maybe I need to rethink what my first flaw is.

My phone buzzed angrily on my chest, and I checked to see a message from Lestrade, littered with sarcasm.

_That's such a shame. You might even be unfortunate enough to catch his attention._

Wait, had he known I'd be the only woman here?

Anger bubbled through my veins at the realisation. Lestrade had literally thrown me into the dog house. The clear fact that I did not belong here would prove to be irresistible to Moriarty. Surely he would've realised that everyone else in this hotel would pay attention to me too. It would mean I'd be spotted as soon as I wore my police uniform, identified as a spy. I was practically a dead woman walking.

How could Lestrade be so reckless? He'd had weeks to think of a plan, and clearly he'd been putting it off. This was definitely the worst idea he's ever had, and I hadn't been stubborn enough to-

'Boyfriend troubles?' All the fury that had been churning through my body instantly turned to ice. My feet rooted to the spot. I knew that voice, _his voice._ I'd heard it when his face had appeared on my TV, smirking, announcing his existence to the world. To Sherlock Holmes, to the police.

James Moriarty had approached me.

I tried to stop my shoulders hunching, or from stammering, or appearing nervous. I knew as soon as I did I would be finished. It took me a moment to look up at him, taking in the sight in front of me.

'Something like that. People are so incompetent these days, are they not?' I batted my eyelashes at him, adopting the most innocent expression I could. He then smirked, a predatory glint in his green eyes. His critical stare travelled from my face to my chest (_pig)_, down the curves of my waist, spotting my turquoise dress and finally finishing by taking in the shoes I was wearing. He took his time responding, his dull Irish accent seeping into his tone.

'Yes… it seems you do your own dirty work, right?' he snuck a fleeting glance at my legs again, and I wondered what he was insinuating. _Oh._ I recalled the bruises currently flowering on my shins, a battle scar from chasing a criminal last week. Maybe I should've worn a longer dress… How had he even noticed in such dim lighting?

I used the opportunity to study him more carefully. His hair was a deep auburn colour, bordering dark brown. His facial features were gaunt, sharp, calculating. Or maybe that was just because I knew he was a mastermind, even though he should look like any other man in a suit. Yet lethality hung around his figure, a physical presence as he spoke. All of my instincts screamed at me to flee.

'Of course, the only way to ensure things are done properly is if you do them yourself.' His Cheshire grin spread, lighting his features as he closed the distance between us, settling his hands on my waist and squeezing. I could feel something hard in his left palm, pressing against my sides. A Victorinox '89 Swiss knife, to be precise -I knew the curvature of the folded knife anywhere. _Shit._

His tone was smooth, seductive as he leaned in, breath hot on my ear. 'I completely agree with your philosophy dear, perhaps we can go outside and discuss this further, Leila?' Wait how did he-

One of his hands released me, dangling my forged ID in front of me with a triumphant smirk. I'd been too focused on examining his facial features to notice he'd lifted my ID out of my tiny purse. He must've had some skill, for I'd been holding the object the entire time.

'I'd be honoured, just be sure to tuck that '89 Swiss Army Knife back into your pocket, wouldn't want to have any accidents now.' My smile faltered, feeling unease embed itself into my body again.

But for a moment I'd had the upper hand, for he washed away the surprise on his face with a blink, simply slipping his arm through the crook of mine.

As we meandered through the crowds, away from prying eyes, I realised that I'd actually managed to fool him. Moriarty hadn't clocked that I was with the police; my façade must've _worked!_

He opened the door carefully, and the cool night air slammed into me, instantly making me wrap my shawl tighter around me. In all honesty, I was still completely terrified, but relieved nevertheless. Maybe Lestrade's idea hadn't been too bad after all, as the police we do need to take the occasional risk…

'Now, why don't you tell me which Police Officer set you up to this?'

_Fuck._

* * *

A/N and that's how Fi ends up in Moriarty's uh...possession. Hopefully that wasn't too shabby for a prologue!

If you like this story, feel free to review, follow, etc. I'll be sure to update as soon as I can.

Until next time!  
KetKat xo


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